If immediately implemented, an entirely unrealistic prospect even by the company’s own admission, with commercially produced solar panels available today, the resulting energy savings gained from not burning fossil fuels could cut the nation’s greenhouse gas emissions in half, according to Solar Roadways projections. And best of all, by simultaneously replacing our crumbling roads and deteriorating power grid, the system would even eventually pay for themselves, according to Solar Roadways.

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It’s easy to get carried away when faced with an idea as potentially game changing as solar road panels. But how well do solar road panels really stack up when reality crashes into theory?

The Big Idea

Solar road panels are made with layers of super-strong glass embedded with photovoltaic cells, electrical wiring and LED lights, which can be used to create signs on the surface directing traffic or alerting motorists to hazardous conditions.

When connected between highways, residential streets, parking lots and driveways, the system of solar panels not only creates a vast, power-collecting network; it also creates a system of delivery that would eliminate the need for above-ground wires and dramatically reduce instances of widespread power failures.

Not So Fast

So what’s holding policymakers and industry leaders from getting behind this idea?

Carrying it to the most ambitious goal put forward by Solar Roadways, namely replacing all paved surfaces within the United States with solar road panels, also isn’t cheap. In fact, it would cost, according to one estimate — brace yourself — $34.5 trillion, according to TreeHugger’s Lloyd Alter. That’s more than twice the gross domestic product of the United States for 2011. By comparison, the cost of building coal-fired power plants producing the same amount of electricity would be about $14 trillion, according to AZoNano.com.

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That’s a large investment for a concept that’s still unproven. Although the Department of Energy gave Solar Roadways a $100,000 to develop a prototype, there are still many questions to be answered: Can the solar road panels delivery the kind of energy that would make them cost-efficient? Would the roads be able to support load of the constant flow of traffic day after day, year after year? Would the glass surfaces create any issues for drivers at high speeds in adverse weather conditions?

A Parking Lot Prototype

Before solar road panels are installed on major highways, they need a significantly smaller road test to prove the concept.

Earlier this year, the Department of Energy awarded Solar Roadways a $750,000 grant, as reported by TreeHugger. That gives the company the funding to build a prototype about the size of a parking lot, which will provide researchers with a constant stream of data to understand how well the idea works in the field.